Processor unit with provision for automated control of processing parameters

ABSTRACT

An imaging device for preparing a printing surface for a printing operation transfers information related to how the printing precursor should be processed to a processor. The processor is automated to make local adjustments according to the information provided. The information can be transferred for each printing precursor or only when changes occur. The transfer is automated.

CROSS REFERENCE TO RELATED APPLICATIONS

This Divisional patent application claims the benefit of applicationSer. No. 10/376,500, entitled “Processor Unit With Provision ForAutomated Control of Processing Parameters” filed Mar. 3, 2003, byManness, commonly assigned to the Eastman Kodak Company and hereinincorporated by reference.

FIELD OF THE INVENTION

The invention relates to processing imaged precursors such 5 aslithographic printing plates. The invention relates specifically toadjusting a processing device for optimal processing performance.

BACKGROUND OF THE INVENTION

In the printing industry a wide variety of printing methods areemployed. Printing methods such as lithographic, flexographic, screenand gravure printing commonly involve preparing an imagebearing printingsurface before commencing printing. Such printing surfaces are oftenprepared in an imaging device which uses an imagewise addressableradiation source to selectively convert or transform areas of a printingprecursor.

In some cases the printing surface is directly ready for use followingimagewise conversion. In most cases further processing is required.Processing may include further exposure to radiation, heating, chemicaldevelopment, chemical etching, a variety of other processes orcombinations thereof. In other imaging industries such as the directimaging of printed circuit boards, imaging devices are commonly coupledwith a processor of some description for further processing ordevelopment of the imaged article.

In the graphic arts industry, imaging and processing steps are usuallyperformed by separate equipment, often provided by differentmanufacturers. For example, lithographic plates, and more particularlythermal lithographic plates are typically imaged in platesetter deviceswhich use high power radiation sources such as lasers for imaging. Afterimaging, plates are removed from the platesetter and either manually orautomatically conveyed to a processor. For negative working thermalplates, processing typically includes a preheat step, in which the plateis uniformly heated to crosslink imaged areas, followed by developmentin a chemical solution that removes non-imaged areas. The plates may bepost-baked to improve their run length on press.

It is important to heat plates evenly during processing. The requiredpreheat consistency over the plate surface for a negative workingthermal plate is preferably in the range of 5° C.-10° C. and mostpreferably less than 2° C. It is also important to maintain any chemicalsolutions used in developing plates in good condition. In mostinstances, the chemical action which occurs during development of aplate weakens or contaminates the chemical solutions used.

Plate processors which provide automatic replenishment of developerchemistry and active control of preheat have been described and/ormarketed by vendors. The inventor has observed that prior art processorsequipped with such automatic function do not integrate well with imagingand processing systems.

WO 01/29620 to Haley et al., describes an integrated processor which hasa pre-heat oven, a developer section, and an optional post-bake section.Preheat is controlled in one embodiment by varying the speed with whichplates pass through the preheat section or the disposition of heatingelements in response to a trigger such as the plate entering the preheatsection. Further measurements of the plate such as width provideadditional control inputs for maintaining even heating.

Stein et al., U.S. Pat. No. 5,716,743 to describes a system formonitoring the condition of a developer solution by measuring a number30 of parameters. Measurements such as conductivity and temperature ofthe developer solution are used along with knowledge of how thechemistry is degraded by processing particular formats and types ofprinting form. The system determines whether to dilute the developersolution with water or to add more developer.

There remains a need for a better apparatus and methods for processingimaged articles. There is a particular need for such apparatus andmethods which can automatically accommodate articles of differentdimensions and/or types. The printing industry has special need for suchapparatus and methods.

SUMMARY OF THE INVENTION

One aspect of the invention provides a method for preparing a precursor.A precursor is imaged in an imaging device and then processed in aprocessor. The processor has a controller which adjusts the processoroperation in accordance with information transferred from the imagingdevice to the processor. In another aspect of the invention theprocessor transfers information to the imaging device to enableadjustment to the imaging process and/or scheduling of imaging jobsaccording to conditions pertaining to the processor.

Another aspect of the invention provides apparatus for imaging andprocessing precursors. The apparatus includes an imaging device, aprocessor and means for transferring information about imaged precursorsimaged by the imaging device to the processor.

Further aspects of the invention and features and advantages of specificembodiments of the invention are set out below.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate non-limiting embodiments of the invention:

FIG. 1 is a schematic depiction of an imaging device and processoraccording to the present invention;

FIG. 2-A shows a marking scheme for a precursor according to oneembodiment of the present invention; and,

FIG. 2-B is a schematic depiction of a imaging and processing systemutilizing the marked precursor of FIG. 2-A.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the following description, specific details are set forth inorder to provide a more thorough understanding of the invention.However, the invention may be practiced without these particulars. Inother instances, well known elements have not been shown or described indetail to avoid unnecessarily obscuring the invention. Accordingly, thespecification and drawings are to be regarded in an illustrative, ratherthan a restrictive, sense.

This invention is described in relation to a system comprising animaging device that is able to image a precursor (such as a media to beimaged) and a processor for processing the precursor. Processingparameters are adjusted according to information supplied to theprocessor by the imaging device. The imaging device may comprise animagewise addressable radiation source, an imaging bed of any suitableconfiguration for holding the precursor, a suitable mechanism forscanning the radiation source across the precursor, and mechanisms forhandling, loading and unloading the precursor.

An internal or external controller or combination thereof, receivesimage data and controls the functions of the imaging device. Suchsystems for imaging lithographic, flexographic, screen and gravure 30printing forms are well known in the art and range from devices thatrequire manual precursor handling to fully automated machines capable ofhandling multiple precursor sizes and types in cassettes or otherstorage that are automatically selected and loaded. Furthermore, imagingsystems are also used in analogous processes to produce other imagedarticles such as printed circuit boards. Such systems are well known inthe art.

The term “precursor” is used herein to refer to an object having asurface that can be imagewise exposed to form a pattern thereon. Thesurface may be coated with an imagable coating. The coating; may be on ametal or synthetic substrate. The substrate may, for example, comprise aflat plate or a cylindrical sleeve substrate. The term “printingsurface” is used herein to refer to the specific instance where theprecursor is to be used in a printing operation.

FIG. 1 illustrates an embodiment of the invention. An imaging device 1,comprises an imaging engine 2 and a controller 3. For satisfactoryimaging performance, it is common for controller 3 to have access toinformation identifying types of precursor with which imaging device 1will be used. This information may, for example, be stored in a datastore of any kind accessible to controller 3. The information maycomprise a table or list of precursor parameters. The information mayinclude precursor type, length, width, thickness, exposure sensitivity,exposure delivered, and data about an image to be imparted to theprecursor by the imaging device.

A conveyor 4 receives precursors 5 and 6 imaged by imaging engine 2 andtransports them to a processor 7.

Processor 7 comprises one or more sections (not shown) for 30 processingthe precursor. Processor 7 may comprise a processing line. In onespecific embodiment of the invention for use with negative-workingthermal lithographic printing plates, processor 7 comprises a prehearoven section and a chemical developer section. A processed printingsurface 8, exits processor 7 and is either manually or automaticallyconveyed to a printing press. Processor 7 includes a processorcontroller which monitors and/or adjusts a number of physical parametersrelated to the operation of processor 7. For example, the processorcontroller may control the application of preheat which is particularlyimportant in processing 10 negative thermal plates. Control of preheatmay be provided by any suitable means such as adjusting an electricalcurrent supplied to one or more heating elements, moving louversdisposed in front of a heater to deflect radiant heat, changing a feedrate of the plates, or moving one or more heating elements. In someembodiments of the invention, heat applied to the leading and trailingedges of a plate is evened out by moving heating elements with the plateas the plate enters a preheating section, and then moving the heatingelements in the direction opposing plate movement as the plate leavesthe preheat section.

Controller 3 communicates with imaging engine 2 via communication path9. Communication path 9 may comprise any suitable data communicationpath such as, for example, one or more signal lines, a signal bus, anoptical fiber, a wireless link, an optical link or any other path fortransferring information. Communication path 9 is also used to permitcommunication between controller 3 and processor 7. Communicationsbetween controller 3 and processor 7 may be carried on the same pathwayor on a separate pathway from communications between controller 3 andimaging engine 2. Those skilled in the art will understand that any of awide variety of communications technologies may be used to providesuitable communication between controller 3, imaging engine 2 andprocessor 7. Controller functions may be moved from one device toanother without changing the principles of operation of the system ordeparting from the invention.

The communication path 9 between imaging device 1 and processor 7transfers information related to precursors 5 and 6 on a continuous orplate-by-plate basis. The information transferred is of use to processor7 in controlling functions related to further exposure steps, heatingsteps, development steps and any other processor functions includingreplenishment of developer chemical solutions.

In an alternative embodiment the communication path between the imagingdevice and processor 7 is provided, at least in part, by markingmachine-readable codes on imaged items to be processed by processor 7.In FIGS. 2-A and 2-B a precursor 10 is shown with a 15 code 11 imprintedin a non-printing area of its surface. Code 11 carries informationrelated to the processing of the plate encoded by some means into areadable form. Code 11 may comprise a bar code, a series of detents onan edge of precursor 10, a number or any other convenient code that canbe marked on a precursor surface and subsequently read 20 by a readerdevice 23 associated with processor 7.

Advantageously the imaging device radiation source is used to writemarks which make up code 11 on precursor 10 as part of or additional tothe image. Should the normal imaging intensity not be sufficient to makea mark with sufficient contrast to detect in reader 23 the mark could beoverwritten several times or imaged at a slower scan speed.

For precursors that do not display a latent image of sufficient contrastto be read by a reader 23, the mark could be made by other means such asan inkjet printing head. Inkjet printers and particularly continuousinkjet printers are commonly used for marking variable data onmanufactured goods. Modular industrial printer systems are commonlyavailable for marking and batch coding. There are many suitable methodsfor imprinting a readable code 11 on an article. Any such method may beused in this invention.

The plate coding system shown in FIG. 2-A and FIG. 2-B does not requireany physical connection between imaging devices 20 and 21 fortransferring the necessary information to processor 7. This system canbe used even in cases where precursors are manually transported and fedinto a processing line or a single processor line serves several imagingdevices.

The general concept of establishing a communication link between one ormore imaging devices and a processor will now be discussed in relationto some specific examples of information that can advantageously betransferred.

EXAMPLE 1 Precursor Dimensions

Advantageously information specifying the dimensions of each precursorare transferred to the processor from the imaging device. While theprocessor may comprise a sensor which permits it to determine precursorlength (e.g. from a sensor on the feed table and knowledge of the feedrate), width and thickness are more difficult to measure in a processor.

Most imaging devices require dimensional parameters to be retained forsetting up the imaging process and/or handling the precursor.Specifically, an imaging device will need to know the length and widthof a plate in order to load it correctly onto the imaging bed. Once itis loaded the imaging systems need to know where the media is placed onthe imaging bed so that the image can be scanned onto the precursor incorrect registration. These dimensions will either be supplied to theimaging device by the operator or determined by the device using asuitable measurement system. Thickness is also an important parameterfor imaging systems that perform geometric correction or employautofocus systems. The required dimensions are also typically listed onthe packaging for the precursor and most imaging devices have facilitiesfor inputting and saving these parameters in memory or other storagemeans. This information is typically unavailable to a processor beingused to process precursors imaged by the imaging devices.

In this example, information obtained in the imaging of a precursorwhich specifies length, width, and thickness of the precursor iscommunicated to the processor. This information is then used by theprocessor to calculate optimal preheat application for the particularprecursor. The preheat control may be in both the longitudinal andcrosswise directions, allowing the preheat delivery to be carefullycontrolled over the entire area of the plate. This is particularlyimportant for situations where many different widths of plate are used.

Information about the area of each precursor can additionally be used tomaintain a record of the total area of precursor processed by theprocessor. This information may then be used for 25 developerreplenishment purposes.

EXAMPLE 2 Precursor Type

While a processor is generally equipped to process a specific precursortype, a situation may exist where a printing plant has several imagingdevices outputting precursors of similar but possibly slightly differentcompositions. As imaging media such as negative working thermal platesbecome more commonplace, it is also possible that their compositions andprocessing requirements will become more generic, possibly allowingplates of different composition to be passed through a common processor.By transferring a type identifier to processor 7 for or with each plateto be processed by processor 7, processor 7 can determine to process aspecific plate differently from other plates. The amount of preheatapplied, the feed rate, and other processor functions can be changed,enabled, or disabled to suit a particular precursor.

Furthermore, since for many printing precursors the performance and runlength on press is at least partially determined by the processingconditions, a precursor targeted for a long run length job can bespecifically processed to promote a longer run length. Specifically if apost-bake oven section is included in the processing line, this sectioncan be selectively enabled or disabled for long run length jobs.Similarly, other properties related to the processing conditions can beenhanced on a plate-by-plate basis if information concerning the job istransferred to processor 7. In the case of a printed circuit boardmanufacturing line, other parameters such as designations as inner orouter layers or line thickness may be provided to processor 7.

EXAMPLE 3 Image Area and Image Constitution

Precursor area is easily determined by a prior art processor frommeasurement of length and width of the plate, but image area is verydifficult to detect at a processor 7. Advantageously the imaging devicecan be equipped to determine a number of parameters related to imagearea that can assist in adjusting a processor for optimal operation.Specifically the actual imaged area is a more relevant parameter fordetermining developer replenishment needs than the simple surface areaof a precursor. “Actual imaged area” means the sum of the areas of allimage pixels on a precursor. Obviously, a page of simple text has animage area significantly different from that of a picture on a darkbackground. Depending on the precursor and processing method, either5the image area or the non-image area is removed in the processing line.In cases where the developer section can be considered as actingessentially only on the part of the image that must be removed to createthe printing plate, accumulating the total actual imaged area over aplurality of processed precursors, is a much more accurate measurement1.0 of developer consumption than precursor surface area.

Transferring from the imaging device to the processor information aboutthe image content can advantageously be used to control the processingconditions. Printers today use a variety of line 15 screen frequenciesand screening methods that vary the minimum dot size considerably.Particularly in the case of FM or stochastic printing, dot sizes can beas small as the single pixel. The processing conditions can be adjustedto best suit the actual image constitution on a particular precursor.Specifically, for fine FM screens, excess preheat may start to fill inbetween the dots while an overactive developer might result insignificant erosion of small dots. In contrast the larger dots of a lowAM screen frequency are much less susceptible to this problem and it maybe beneficial to apply additional preheat to achieve greater run lengthon press. The information transferred may comprise a measure of smallest25 dot size, screen frequency or the like.

EXAMPLE 4 Exposure Level

For successful preparation of a printing surface the combination ofimaging exposure and processing activity is often a 30 critical balance.Specifically in the case of negative working thermal plates, it is thecombination of imagewise exposure and preheat that ensures that theplate will be correctly exposed to provide a desired image quality andrun length. A lower or higher exposure during imaging may have someadvantages in printing a particular image but if not compensated by apreheat adjustment, the printing surface may end up being under orover-exposed. Again by providing a plate-by-plate transfer from theimaging device to the processor of information which indicates anexposure provided to each plate by the imaging device, the processor canautomatically adjust processing conditions for each plate to match theimaging exposure.

EXAMPLE 5 Processor Maintenance

Information may also be transferred from the processor to the imagingdevice. This information may be used in various ways by the imagingdevice. If the processor requires a developer replenishment it couldassert a busy flag, indicating to the imaging device or devices feedingit that it is not ready to receive a precursor. This is particularlyadvantageous for precursors where the latent images formed by imagewiseconversion have limited persistence or cases where imaged precursors canbe degraded by exposure to ambient light. The imaging device may beconfigured not to start imaging a precursor if the processor statusinformation. indicates that the processor is not ready to process theimaged precursor.

The processor could also communicate to the controller when chemistrychanges or other maintenance is done, thus allowing the controller tomodify the subsequent processing conditions. Furthermore, conditions ofthe chemistry, such as conductivity, are sometimes measured by theprocessor and could be used for further adjustment of the processing orimaging processes.

Thermal lithographic plates are used as examples in the foregoingdescription to illustrate the operation of the present invention.However, the invention is applicable to other modes of printing andimaging such as flexography, gravure, and screen-printing. The inventionmay be applied in any case where a processing step follows an imagewiseexposure step, particularly when the steps are at least partiallyinterdependent. The invention is also applicable to the processing ofsleeve forms that are used in rotogravure, flexographic andscreen-printing. These sleeve forms are usually processed “in-the-round”in specialized equipment.

Similarly, the invention may be applied in an apparatus formanufacturing circuit boards. In this case, a processor may be providedwith information regarding parameters of circuit board precursors to beprocessed such as different line widths, thickness of substrates, andthe like. The processor automatically adjusts processing conditionsbased upon such parameters.

While the invention has been described in terms of a plate-by-plateinformation transfer, the transfer of information from an imaging deviceto a processor could also be done on a batch basis, thus grouping anumber of like precursors together and only communicating changes whennecessary.

Where a component (e.g. a software module, processor, assembly, device,circuit, etc.) is referred to above, unless otherwise indicated,reference to that component (including a reference to a “means”) shouldbe interpreted as including as equivalents of that component anycomponent which performs the function of the described component (i.e.,that is functionally equivalent), including components which are notstructurally equivalent to the disclosed structure which performs thefunction in the illustrated exemplary embodiments of the invention.

Those skilled in the art will appreciate that the conception on whichthis disclosure is based may readily be utilized as a basis for thedesign of other apparatus for carrying out the several purposes of theinvention. It is most important, therefore, that this disclosure beregarded as including such equivalent apparatus as do not depart fromthe spirit and scope of the invention.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof; but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention. This invention is inclusive of combinations of theembodiments described herein. References to a “particular embodiment”and the like refer to features that are present in at least oneembodiment of the invention. Separate references to “am embodiment” or“articular embodiments” or the like do not necessarily refer to the sameembodiment or embodiments; however, such embodiments are not mutuallyexclusive, unless so indicated or as are readily apparent to one ofskill in the art. The use of singular and/or plural in referring to the“method” or “methods” and the like are not limiting.

1. An apparatus for processing one or more precursor batches ofidentically coated precursors, the apparatus comprising: an imagingdevice for imagewise converting the precursor according to the imagedata to yield an imaged precursor the thermal imaging device having anassociated imaging device controller for receiving image data definingan image to be imparted to a precursor by the imaging device; aprocessor for processing the imaged precursor, the processor having anassociated processor controller; and means for automaticallytransferring digital information about the precursor from the digitalthermal imaging device controller to the processor controller. 2.Apparatus according to claim 1 wherein the means for automaticallytransferring digital information about the precursor from the imagingdevice to the processor comprises means associated with the digitalthermal imaging device for writing a code on the precursor and meansassociated with the processor for reading the code.
 3. Apparatusaccording to claim 1 wherein the means associated with the digitalthermal imaging device for writing a code on the precursor comprises anaddressable radiation source.
 4. Apparatus according to claim 1 whereinthe means for transferring digital information is configured to transferdigital information comprising one or more of: a precursor type, aprecursor length, a precursor width, a precursor thickness, a precursorexposure sensitivity, an imaging exposure delivered to the precursor,and data about an image imparted to the precursor by the digital thermalimaging device.
 5. A digital thermal apparatus for processing one ormore precursor batches identically coated precursors, the apparatuscomprising: a digital thermal imaging device for imagewise convertingthe precursor according to the digital image data to yield an imagedprecursor the digital thermal imaging device having an associatedimaging device controller for receiving digital image data defining animage to be imparted to a precursor by the imaging device; a processorfor processing the imaged precursor, the processor having an associatedprocessor controller; and means for automatically transferringinformation about the precursor from the imaging device controller tothe processor controller, said means comprising means associated withthe imaging device for writing a code on the precursor and meansassociated with the processor for reading the code.
 6. The apparatusaccording to claim 5 wherein the means associated with the imagingdevice for writing a code on the precursor comprises an addressableradiation source.
 7. The apparatus according to claim 6 wherein theaddressable radiation source comprises adjusting physical locations ofone or more heating elements disposed to heat the precursor.
 8. Theapparatus source according to claim 5 wherein the means for transferringinformation is configured to transfer information comprising one or moreof: a precursor type, a precursor exposure sensitivity, and an imagingexposure delivered to the precursor.
 9. The apparatus according to claim5 comprises a width measurement mechanism for determining a width of theprecursor, and the method comprises measuring a width of the precursorusing the width measurement mechanism and including the measured widthin the information.
 10. The apparatus according to claim 5, theprecursor is one of a lithographic printing surface; a screen; a gravureprinting surface including a gravure cylinder; a letterpress printingsurface; and or a flexographic printing surface.
 11. The apparatusaccording to claim 5, further comprising a processor for processing theitems by a process involving a developer chemistry; and maintaining anindex representing a status of the developer chemistry based upon theactual imaged areas determined for the processed items and replenishingthe developer chemistry when the index indicates that the developerchemistry requires replenishment.